The alkanesulphonic acids and their salts have numerous industrial applications, especially as detergents, emulsifiers, esterification catalysts and hardeners for some resins.
Industrially, alkanesulphonic acids are most often produced from alkanes by sulphonation or by chlorosulphonation. These two routes of synthesis have, however, the disadvantage of leading to the formation of by-products which are sulphonated on the various carbon atoms of the hydrocarbon chain. Moreover, the hydrolysis of alkanesulphonyl chlorides generally leads to alkanesulphonic acids which are more or less intensely coloured and to the undesired production of hydrochloric acid.
In the last few years, much work has been devoted to the atmospheric photochemistry of sulphur-containing organic compounds (thiols, sulphites, disulphites) which are, in trace amounts, atmospheric constituents of biogenic origin, or, more often, pollutants arising from energy production technologies. Most of these photochemical studies were carried out in the gas phase at low pressure (.ltoreq.1 atm) in the presence of air, oxygen, an eluent gas and sometimes nitrogen oxides. All the results obtained mention the formation of sulphur dioxide and sulphonic and sulphuric acids, as well as other products which vary according to the conditions employed.
Research into solution photooxidation of sulphur-containing organic compounds has almost exclusively been devoted to the photooxidation of sulphides in the presence of photosensitizers for the preparation of sulphoxides and sulphones. Two articles, one by R. W. Murray et al. (J. Org. Chem. Soc., 37, 1972, pp. 3516-3520) and the other by E. L. Clennan et al. (Tetrahedron Lett., 35, 1994, pp. 4723-6) relate to the formation of thiosulphinates and of thiosulphonates by photooxidation of disulphides in the presence of photosensitizers.